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Ryan Slominski edited this page Oct 16, 2017 · 9 revisions

Java Web Socket Specification (JSR 356) "Irregularities"

  • Accessing request metadata such as determining the client IP address or request headers (User Agent, X-Forwarded-For, etc.) in a web socket server end point is not well defined by the spec and is generally Application Server (Tomcat vs GlassFish vs Wildfly, etc.) dependent. A complex ThreadLocal approach can be used to avoid proprietary approaches: https://github.com/javaee/websocket-spec/issues/235.
  • Writes (both Synchronous and Asynchronous) are not required to be thread safe per specification. Most implementations are though as it makes sense that it would be. Tomcat is a notable exception: https://bz.apache.org/bugzilla/show_bug.cgi?id=56026. In Tomcat all writes must be externally synchronized on the session if multiple threads are writing.
  • The server side API does not handle ping/pong automatically and simply exposes a method for manually sending a ping and listening for a pong. This means you must create your own timer thread: https://github.com/javaee/websocket-spec/issues/176

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